Retractable pitot static tube



June 24, 1941. w, s, DIEHL 2,246,510

RETRACTABLE PITOT STATIC TUBE Fiied July 6, 19:59 2 Sheets-Sheet 1 INVENTOR WALTER S. DIE HL BY "19 ATTORN? W. 5. DIEHL RETRACTABLE PITOT STATIC TUBE Filed July 6, 1939 June 24, 1941. 2,24 ,510 1 a zs 32 m mm w Mil I O I!" I It INVENTOR WALTER 5. 0/5/11.

ATTORN 2 sheets sh et g Patented June 24, 1941 RETRACTABLE PITOT STATIC TUBE Walter S. Diehl, United States Navy Application July 6, 1939, Serial No. 283,030 (01. 244-1) (Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) 4 Claims.

The present invention relates to Pitot static tubes and particularly to that class of tubes for static and impact pressure readings.

In the present day method of securing a high degree of accuracy in staticand impact pressure readings, the Pitot static tube is mounted on a boom extending approximately one-half chord length ahead of an aeroplane wing. From experience it has been found that the above arrangement is only advantageous where there is abundant space and where the aeroplane is handled on the ground under favorable conditions. The boom method of mounting the Pitot tube is disadvantageous for the reason that it is subject to fouling and damage from various other causes.

It is therefore an object of the present invention to provide a Pitot static support tube that may be adjustable between. extended and retracted positions and one that will insure satisfactory readings in an extended position.

Another object of the present invention is the provision of a device that is manually or mechanically operated, and one that is positive and firm. 1

A further object of the present invention is the provision of a retractable Pitot static tube that may be properly handled on the ground in a retracted position under unfavorable conditions.

A stillfurther object of the present invention 7 is the provision of locking means for securely locking the Pitot static tube in either an extended or retracted position.

A still further object of the present invention is the novel arrangement of means for imparting impact and static pressure to the Pitot tube at all times and for preventing fouling and kinking of the pressure tubes during extended or retracted movement of the Pitot tube.

With these and other objects in view the invention consists in the combination and arrangement of parts to be hereinafter described and claimed, reference being had tothe accompanying drawings in which the numerals of reference designate similar parts in the several views and wherein:

Fig. 1 is a side elevational, fragmentary view of an aeroplane wing, illustrating my novel tube mounting and operating means;

Fig. 2 is a fragmentary plan view of an aeroplane wing illustrating the Pitot static tube in retracted position and the arrangement of the operating means for said tube;

Fig. 3 is an enlarged detail view ofthePitot static tube in retracted and locked position and illustrating the spring and pin means for holding the Pitot tube in extended position, the guide tube housing and slotted guide tube being shown in section, portions being shown broken;

Fig. 4 is an enlarged detail view, similar to Fig. 3, and illustrating the Pitot static tube in extended position, portions being in section;

Fig. 5 is a sectional view taken on line 5-5 of Fig. 3 illustrating the assembly of the tubes and the guide pin in the guide slot;

Fig. 6 is a sectional view taken on line 6-45 of Fig. 4 and illustrating the slidable tube in locked position; i

Fig. '7 is a fragmentary plan view illustrating the Pitot static tube and its associated mechanism in extended, locked position;

Fig. 8 is an enlarged detail view of the arrangement of pulleys, cable, cable finger, guide ring tubes and pulley block; and

Fig. 9 is an enlarged view of the cable finger.

Referring to the drawings, I have illustrated my device as manually operated and I would have it distinctly understood that the device may be mechanically operated if desired. In the drawings, the numeral It) represents an aeroplane wing in which is mounted in any suitable manner a cylinder ll, one end of which is provided with a wall l2 having a reduced bore l3. Within the cylinder I2 is mounted a tube l4 that is provided with a slot l5 and it is to be noted that the end iii of the tube 14 is spaced from the inner Wall of cylinder I2 providing a circular opening I8 for a purpose to be later described. Within the tube it. is mounted for slidable movement 2. Pitot static tube 1'9 carrying a pin 26 (Fig. 3) that is freely slidable in slot it. One end of the Pitot static tube It has a depending L-shaped head portion 2!, the opposite end 22 having a depending portion 23, and it is to be noted that the end portion 22 is adapted for locking engagement with a spring clip 24 that is secured to a longitudinal brace 25 of the wing in any suitable manner. Fixedly mounted on the Pitot static tube i9 adjacent the end 22 of the tube is a disk 26. A floating disk 2'! is also mounted on the tube is, and interposed between the disks 26 and 21 is a compression spring 23. A finger 29 provided with apertures 30 and 3! (Fig. 9) is fixed to the disk 26, the tube passing through the aperture 30, the diameter of which is in excess of the diameter of the tube l9 so as to permit the turning of the tube I 9 either to the right or left for a purpose presently to be described.

Within the aeroplane wing I0 is mounted in any suitable manner a plurality of pulleys 32 and a ring 33 that is carried by a plate 34, one end of which is rigidly fixed in any suitable manner to the tube I9, guide pulley 35 and a floating pulley block 36 that is provided with cable pulleys 31 and a guide wheel 38. Trained around the pulleys 32 and 31 is a cable 39, the ends of the cable respectivel -being. securely fixed to axles 49 of the pulleys 32. The aperture 3| of the finger 29 is fixedly positioned on the cable 39 as illustrated in Fig. 8. Within the tube 19 and trained through the ring 33 and around the guide wheels I 38 and 35 are pressure tubes 4| and it is to be noted that the pressure tubes appear'to be one tube, this being accomplished: by binding.v the tubes together in order that they may pass over guide wheels 38 and 35 smoothly.

In the operation of my novel device, the operator grasps the Pitot tube at 2: andpulls the tube l 9, which due to the pull is released from the clip 24 out to its fullextended position, When it is givena-slight turn to 'the'right or left, wherein the pin 2| engages the face I6'of tube Hi. Near the end of the outward travel of the tubeis, the collar 21 engages the inner end of the cylinder I I so that the final movement of the tube slightly compresses the spring 23. The tube it is thus held against backward rotation by the force exerted by-the compression springflt. During the movement of the-tube to extended position, motion' isimparted to the cable 38 through the medium of the-fixed finger 29, moving the pulley block 36 and the guide ring 33. As the movement continues, the pulley block 35-movesto the left and the pressure tubes, during movement are prevented from kinking by the guide ring 33 andguide wheels 35-and 38. To return the Pitot tube to retracted position, the tubeis turned until the pin 29 registerswith-theslot i5,and inward force is exerted-to the tube until the-end 22 engages the clip-24: Duringthe retracting movement the cable 38, pulleyblock- 36 and guide ring 33 andpressure-tubes 4i move "as the tubel9 moves, the-pulley block 35 assumin'g its central positionas illustratedin Figs; 2 and 8;

It, will be understood that the above description' and accompanyingdrawings comprehend o-nly'the general and-preferred embodiment of m invention and that various changes in construction, proportion and "arrangement of parts may be made within the scope of the appended claims without sacrificing any of the advantages of my invention.-

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for'governmental purposes-without-the payment of any royalties thereon or therefor.

Iclaim:

1; In combination with an aircraft structure a Pitot tube slidably mounted for movement from an extended'operative position to a retracted position, a part ofsaid tube at all times being housed within the aircraft structure, a member mounted on the Pitot tube within the aircraft structure, a pulley, means for mounting the pulley within the aircraft structure for movement in a path generally parallel to the path of movement of the Pitot tube; means connecting said pulley to said member including means for moving the pulley one-half the movement of "said member and in the same direction, pressure and impact tubes secured to the aircraftstructure in the gen-= eral neighborhood of the position of'therear; end of the Pitot tube whenin retracted position; then passing over said pulley and then connected to the rear end of the Pitot tube whereby slack is taken up in said tubes as the Pitot tube is extended and retracted.

2. In combination with an aircraft structure a Pitot tube slidably mounted for movement thereon from an extended operative position to a retracted position, a part of said tube at all times being housed within the aircraft structure, a member mounted on the Pitot tube within the aircraft structure, a helical spring encircling said Pitot tube-to the rear of said member and secured at one end to said member, a finger slidably mounted on said Pitot tube and secured to the other end of said spring, a pulley means for mounting the pulley within the aircraft structure formovement in a path generally parallel to the pathofmovement of the Pitot tube, means connecting said pulley to said finger including means for moving the pulley one-half the movement of said member and in the-same direction, pressure and impact tubes secured to theaircraft structure in the general. neighborhood of the p0- sition of ithe rear end of the Pitot tube When in retracted position, then passing over said pulley and then connected tothe rear end of the Pitot tube whereby slack is taken .upin said tubes as the Pitot-tube is extended andretracted.

3. In combination with an aircraft structure, a Pitot tube slidably mounted for movement thereon from an extended operative position to a retracted positioma part of said tube at all times being housedwithin the aircraft structure, a finger mounted on the Pitot tube and movable with said Pitot tube within. said structure, a pulley mounted Within the structure and adjacent the rearward position of said finger; a second-pulley adjacent the forward position of said'finger when the :Pitot tube-isin' extended position, a floating rnember, means for mounting-said-member for" movement-in a path generally-parallel to a-line passing through-said'pulleys, at least three pulleys mounted on-said member, a securing means mounted on the airplane structure adjacent the first mentioned pulley, cables secured to said means and passing around oneof the pulleys on the floating member, thence around the first named pulley, then aroundthe' second named' pulley;- then around another pulley-on the fioat= ing member, then secured to the aircraftstructure adjacent said second named-pulley,- means securing the'finger to said-cablebetween the first and second pulleys, means for-reversingthe direction of motion of said cable-between the-first two pulleys and the-fio'ating member; astatic being housed within-the aircraft-structure; a-

member secured to said Pitot-tubew-ithin the aircraft structure, a' helical spring-encircling said Pitot-' tubeto-the-rear-of said memberand secured at oneendto-said member, a'iinger slide bly mounted on said Pitot tube-and secured to' the--other---end of=said --spring; a'pulley mounted, within the-structureand adjacent-in rearward secured to said means and passing around one 10 of the pulleys on the floating member, thence around the first named pulley, then around the second named pulley, then around another pulley on the floating member, then secured to the aircraft structure adjacent said second named pulley, means securing the finger to said cable between the first and second pulleys, the means for reversing the direction of motion of said cable between the first two pulleys and the floating member, a static pressure tube and an impact tube both secured to the airplane structure adjacent the first mentioned pulley, then trained around a pulley on said floating member, then secured to the sliding Pitot tube device whereby when the Pitot tube is moved to extended or retracted position the floating member is displaced, thereby taking up slack in said tubes.

WALTER S. DIEHL. 

